Conventional halogen-based MR16 lamps include certain designs. In many cases, for aesthetic purposes, perceptible radiation is emitted in a direction substantially opposite that of the projection direction. For example, MR16 lamps on “track lighting” systems used in higher-end restaurants employ this characteristic. This backward-emitted light is actually the residual effect of visible light leakage through the dichroic filter applied to the reflector in many MR16 lamps. The multi-layered reflector causes different regimes of the visible spectrum to be transmitted (backwards) or reflected (projected), so that the backward emitted light has a “rainbow” appearance which is pleasing to the eye and contributes positively to the overall ambience. A side-view photograph of such a halogen lamp in operation is shown below (left).
Unfortunately, halogen lamps are extremely inefficient (˜10-20 lm/W, or ˜5% of theoretical light-generation efficiency) and are thus not cost-effective to operate. LED reflector lamps, on the other hand, exhibit efficacies up to 60 lm/W (˜20% efficient) and correspondingly lower operating costs. However, LED reflector lamp designs today substantially block the backward emitted light, and thus are unable to provide an aesthetic feature that is highly valued by many lighting designers and end users (see above: middle, right). Thus, legacy LED reflector lamps are not able to be deployed in certain applications, meaning reduced market adoption for energy-efficient lamps and thus slower reduction of greenhouse gas emissions associated with electricity consumption for lighting.
Prior descriptions of LED lamps to effect decorative illumination require additional LEDs to provide such illumination directly (e.g., U.S. Pat. No. 7,597,456). The additional LEDs add cost and complexity to the LED lamp. What is needed is a cost-effective LED reflector lamp solution that provides for backward emitted light. The aforementioned legacy technologies do not have the capabilities to perform apportioning of the optical projection paths in an LED lamp. Therefore, there is a need for improved approaches.